1. Technical Field of the Invention
The present invention pertains in general to the planning and implementation of cell sites within a cellular telephone network, and more particularly, to providing pico-cell coverage within a building and extending coverage from a macro-cell located outside the building to inside the building using shared equipment.
2. Description of Related Art Cellular telephone service is becoming increasingly ubiquitous with subscribers expecting uninterrupted coverage throughout a service area. Frequently, however, subscribers encounter disruptions in cellular telephone service as they enter a blind spot where the propagation of radio waves is inhibited by a physical obstruction. One location where this disruption in service frequently occurs is within a building where cellular telephone coverage is either spotty or nonexistent. To provide uninterrupted cellular telephone service within a building, cellular telephone planners incorporate a pico-cell located within the building in addition to a macro-cell which is located outside the building. In designing the pico-cell, the cellular telephone provider deliberately creates the pico-cell to be distinct from the macro-cell by assigning it a separate set of radio frequencies. Thus, a cellular telephone user who is using a cellular telephone prior to entering the building is serviced by the macro-cell located outside the building. Upon entering the building, a handoff of the cellular telephone call is made from the macro-cell to the pico-cell with the pico-cell servicing the cellular telephone user while inside the building.
In some situations, such as in airports and high-rise office buildings, the pico-cell can experience great capacity demands when a large number of cellular telephone users attempt to use the system at the same time. These locations are referred to as hot spots. In these areas, the cellular telephone provider needs to increase capacity to ensure that the increased demand is met. It would be advantageous therefore, to extend the macro-cell coverage of a cellular telephone network present outside a building to inside the building which is also serviced by a pico-cell in order to meet peak capacity demands. Furthermore, it would be advantageous to extend the macro-cell coverage inside the building by sharing the equipment used by the pico-cell.